1. Field of the Invention
This invention relates to a method of plating treatment, particularly to a method of applying partial plating to the surface of a workpiece of such material as metal, ceramic or plastic.
2. Description of the Prior Art
Method are known for forming plated electrically conductive coatings which serve as electrodes or circuit patterns in the production of electronic parts, circuit boards or the like, there is a plating method. There are two plating methods: electroplating and electroless plating. Whether one plating method or the other is employed, a plated coating will be formed on the entire surface of a workpiece unless some measure is taken. However, it is important to form said electrode and circuit patterns on localized portions of the surface of an electronic part or circuit board; therefore, in forming such electrode and circuit patterns, there arises a need for taking measures to ensure localized formation of a plated coating.
Japanese Pat. Application Laid-Open Specification No. 162789/1985 filed by the assignee of this application discloses a method of locally forming a plated coating on the surface of a workpiece by using an elastic member of natural rubber, cork or the like placed in close contact with part of the surface of said workpiece to thereby prevent a plating solution from contacting the area covered by the elastic member. In a typical example of the disclosed method, to form a plated coating on a board having a through-hole except on the inner peripheral surface of said through-hole, said board is subjected to a plating treatment with a plug-like elastic member fitted in the through-hole. According to this technique disclosed in said specification, however, it has been found that the following problems are encountered.
It frequently happens that an elastic member fitted in the through-hole slips out of the through-hole depending on its shape and size, so that plating is applied also to the inner peripheral surface of the through-hole where plating is not desired.
On the other hand, to make it difficult for the elastic member to slip out of the through-hole, an elastic member of relatively large diameter could be used. In this case, however, it becomes difficult to insert the elastic member into the through-hole, so that the operation of insertion is not efficient. Further, if a material of relatively low elasticity is used, the workpiece and/or the elastic member tends to break during insertion into or extraction from the through-hole.